I am working in Quantum GiS and I have a lot of this problem like in image. The two line are separated but i want a continuous line. What rule should I choose in Topology Checker? I want to know all the separated line, so i can fix them.


1 Answer 1


Use the Must not have dangles rule, and if lines are always supposed to meet end to end rather than having an end just touch another line anywhere, use the Must not Intersect or Touch Interior. All line ends that do not meet another line end will appear as a topology error and with the topology tools you will have the option to snap, extend or trim dangle ends, or split lines that touch or cross other lines. Snap would work best for the line pair you showed. Where your lines actually should terminate in a dangle (such as cul-de-sacs and stubs in a road network), you can mark those dangles as an exception so they will no longer show up as a topology error.

See the topology rule illustrations and explanations in this help topic.

  • This user makes no mention of using ArcGIS for Desktop and I think will be expecting a QGIS answer. If you are just using ArcGIS documentation to access better illustrations and explanations that is probably OK but I think you should preface your answer with something like "Look for a rule like Must not have dangles in the QGIS Topology Checker.
    – PolyGeo
    Feb 15, 2015 at 21:55
  • I missed the QGIS tag, and I get shot down every time I answer one, so normally I try not to answer these questions. I can only answer with Esri knowledge. In any case, the concepts and illustrations behind these rules should be identical in both Esri and QGIS. Feb 15, 2015 at 22:37
  • I think the GIS software (and version) should always be written in the body of the question to better frame it. If a question is tagged well that is a bonus. It's great to have you here answering questions.
    – PolyGeo
    Feb 16, 2015 at 0:44
  • 1
    @PoPo You are supposed to mark Richard's answer as accepted, since you stated that it helped you solve the problem. That's how you reward people who make an effort to answer your questions. Please see gis.stackexchange.com/tour Feb 18, 2015 at 13:41

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